Corrosion inhibitor composition



Patented Aug. 21, 1951 UNITED STATES CORROSION INHEITOR' COMPOSITION NoDrawing. Application June 8, 1950, Serial No. 166,063

16 Claims. (01. 2555-892) This invention relates to corrosion inhibitorsand more particularly to corrosion inhibitors for aqueous solutionswhich normally corrode metals.

Stabilized rosin amines such as hydrogenated rosin amines anddehydrogenated rosin amines are known to have the property of inhibitingcorrosion of metal surfaces when applied to the surfaces in an unctuoussolvent. Although these stabilized rosin amines and their salts havebeen found useful in unctuous solvents, they have not been found to besuitable per so as inhibitors of corrosion in aqueous solutions as inmineral acid solutions used in the cleaning of metals. Certainderivatives of stabilized rosin amines such as the ethylene glycolethers of the ethanol rosin amines are, on the other hand, shown incopending,application of Edward A. Bried, Serial No. 39,801, filed July20, 1948, now U. S. Patent No. 2,510,063, to be highly eflicientinhibitors for mineral acid solutions.

Now in accordance with this invention, it has been found that aqueouscompositions normally corrosive to metal surfaces are inhibited towardcorrosion of such metal surfaces when they contain dissolved ordispersed therein in small amounts a composition consisting of to 50% ofa primary rosin amine and a complement of a material of the formulahaving a molecular weight between about 500 and about 2000, where R is aradical selected from the group consisting of abietyl, hydroabietyl, anddehydroabietyl and m and n are integers such that the molecular weightis within the above-designated range. The inhibitor compositions of thisinvention are particularly effective as inhibitors for mineral acidssuch as hydrochloric acid used in oil well acidizing and in boilercleaning. Their effectiveness in inhibiting corrosion of ferrous metalsby such mineral acids is much greater weight for weight than theeffectiveness of any of the components taken separately. There is thus asynergistic effect in the compositions as shown hereinafter in theexamples which illustrate the use of the compositions of this invention.

As examples of the present invention. tests were made on the corrosionof low carbon steel plates in inhibited and in uninhibited hydrochloricacid solutions at 165 F. for four hours. The technique of carrying outthe tests was as follows:

To samples of 15% hydrochloric acid were added in an amount of 0.2% byweight of the acid the materials designated in Table I. The inhibitedacids were then thoroughly stirred at 165 F. to eifeot completedispersion of the added inhibitor materials. To each of these solutionswas added a weight. freshly polished. low carbon steel plate (2 inchessquare) at 165 F. and the solutions were maintained at that tempera turefor four hours. The plates were then weighed for weight loss as ameasure of corrosion. For comparison, an uninhibited hydrochloric acidsolution was also tested. The per cent corrosion is calculated bydividing the per cent weight loss of the plate in the inhibited acid bythe per cent weight loss of the plate in the :ngnhibited acid. Theresults are recorded in the Table its i o iii" Inhibitor Compositioninhibitor 1g Amount of Moi. Wt. Percent 0.2% 0.1%

Dglgfigogenated rosin m 2 lolgethylenegl ool at or cldietheno degdgggemted rosin m 3 Po] a- -Y-aa- 100 3.09

at are diethenc degi r gseneted resin 1 ma 4 sa as-sat res" et erodietlmno degg gsensted rosin 8m 5 ra asgiasrsraai' at ero diotlmuo deggggsenated rosin 767 no 8 "on" L2 Inn." 6 Pol eth lone l col et eroFdiethurEoYdegg ggsenated rosin m we 0 9 Lggg 3 mung 1,3333 0.01 1.51

0 eouu 9 80 Jounc ggg 55 0.79 1.17

o scum gum mm m 53 0.84 1.17 11 03;; 53 0-81 ours w 00m sound 253 5 Hgggggfi l,% 9g 13 g 1.38 u 14 gogoogc 2 1-17 0 30 C 15 Oomaounc 767 0-91Similar tests have shown that there is a synergistic eflect in theinhibitor properties of ordisuch as distilled water, tap water, boilerwater,

water used in automobile radiators with or without alcohols, glycols,and other freezing point depressants used in automobile radiators,hydrochloric acid solutions used for oil well acidizing and descaling ofmetals, aqueous brine solutions containing sodium chloride, mixedcalcium chloride-magnesium chloride and similar brines used forrefrigeration purposes, whether or not containing ammonia. It is mostoutstanding in the case of hydrochloric acid solutions.

The class of materials, which when used in combination with the variousrosin amines gives the enhanced corrosion inhibiting effect, is apolyethylene glycol compound of the general formula N)CH:CH1O)-H v Rwherein R is the abietyl, hydroabietyl. or dehydroabietyl group. Suchcompounds having a molecular weight of at least 500 will have asumciently long polyethylene glycol chain to make the useful compoundswater-dispersible.

The synergistic effect will be noticeable with compositions having from5 to 50% rosin amine or stabilized rosin amine in combination with acomplementary amount of the polyethylene glycol compound but since rosinamine is not very soluble in water or strong mineral acids, as much asv50% of the rosin or stabilized rosin amine will ordinarily only be usedin compositions for use in dilute acids such as l to 2% hydrochloricacid. For use in solutions of higher mineral acid concentration or insolutions of very low or no free acid concentration, the rosin amine orstabilized rosin amine will be used in lower percentages of thecomposition, say, from 5 to 25%.

The amount of inhibitor composition used in aqueous solutions willordinarily be quite low. Only sufllcient to inhibit corrosion willordinarily be used and this will vary from about 0.01 to about 5% of theaqueous solution depending upon the particular inhibitor composition.For the most active inhibitors, as may be selected from the table, theamount ordinarily used will be about 0.1 to 3% based on the weight ofthe aqueous solution to be inhibited.

The ethylene oxide condensates of the rosin or stabilized rosin aminesare made by condensing ethylene oxide with rosin amine or stabilizedrosin amine. The diethanol rosin amine-ethylene oxide condensate isprepared by first adding the theoretical amount of ethylene oxide to theamine in the absence of a catalyst and subsequently adding the catalystand condensing further with ethylene oxide until the desired amount ofethylene oxide has reacted to give a composition of molecular weightbetween 500 and 2000. Such products are balsamlike compounds and aredescribed in applicants copending application Serial No. 66,146, filedDecember 18, 1948, now U. 8. Patent No. 2,510,284.

The initial product of condensation of the amine with ethylene oxide isan ethanol rosin amine having the formula CHICHIOH where R is theorganic radical of the rosin amine. The polyethylene glycol derivativesof the rosin amines of the compositions of this invention are theproducts of further reaction with ethylene oxide in which the alcoholgroups of the initial product react with the formation of etherlinkages. Thus, the product of reaction of rosin amine with seven molesof ethylene oxide is a substance of the general formula bcmcmonn Rwomonlonn where the sum of m and n equals about seven.

In these formulas where R. is the organic radical of a rosin amine, itis intended that the radical shall include the abietylradical, thedihydro abiety] radical, the tetrahydroabietyl radical, and thedehydroabietyl radical.

The rosin amines from which the glycol ethers of the diethanol rosinamines of this invention are prepared are the rosin amines which areprepared by reacting ammonia with a natural rosin or a modified rosin toform the nitrile from the carboxyl group in the rosin and thenhydrogenating the rosin nitrile or modified rosin nitrile to form theamine. The preparation of the nitrile may be carried out by passinggaseous ammonia into the molten rosin material and vaporizing the wateras fast as it is formed in order to remove the water from the reactionmixture. Dehydration catalysts may be used to facilitate the reactionwith ammonia, if desired. The nitrile is preferably purified byneutralization or distillation to make it suitable for hydrogenation tothe amine as the presence of acidic materials frequently destroys thehydro-- genation catalyst. The nitrile may be formed from any naturalrosin or modified rosin such as gum rosin, wood rosin, hydroge iatedrosin, dehydrogenated or disproportionated rosin, or heat-treated rosin.The rosin nitriles may likewise be made from the rosin acids which aremajor constituents of these rosins such as abietic acid, dihydroabietic,dehydroabietic acid, and tetrahydroabietic acid.

The resin acid nitriles prepared from the natural or modified rosins orthe corresponding rosin acids are readily hydrogenated to the amines.The hydrogenation is usually carried out by heating the rosin nitrile atabout C. to 200 C. with a Raney nickel catalyst under hydrogen pressureup to about 8000 lb./sq. in. The hydrogenation may also be carried outusing other catalysts such as Raney cobalt, supported nickel or cobaltcatalysts and noble metal catalysts such as platinum, palladium,palladium-on-carbon, or reduced platinum oxide. The reaction may becarried out under hydrogen pressure of from about 200 to 8000 lb./sq.in. and at a temperature of from about 20 C. to about 200 C. Solventsmay be used if desired and are preferable at the lower temperatures. Thehydrogenation may also be carried out in the presence or absence ofammonia. Although the hydrogenation is ordinarily carried out only tothe extent of hydrogenation of the nitrile group which hydrogenatesquite readily, the hydrogenation may also be carried out under suchconditions of temperature, pressure, and time of hydrogenation as tohydrogenate the rosin amines which are produced to convert them tohydrorosin amines which correspond to the amines produced fromhydrogenated rosin via the nitriles.

For convenience of expression in this specification, the abietyl,hydroabietyl, and dehydroabietyl radicals are referred to with theintention that they be considered broadly as covering rosin materialscontaining those radicals as major constituents. Thus, the productsderived from rosin are considered to have the abietyl radical as a majorconstituent, the products derived from hydrogenated rosin are consideredto have hydroabietyl radicals as the major constituent, anddehydrogenated rosin is considered to have dehydroabietyl radicals asthe major constituent. Abietylamine is thus considered synonymous withrosin amine, hydroabietylamine is considered synonymous withhydrogenated rosin amine, and dehydroabietylamine is consideredsynonymous with dehydrogenated rosin amine. It is not intended, however,to exclude the possibility of minor amounts of each of the various rosinamines in any of the rosin amines referred toby specific chemical names.

What I claim and desire to protect by Letters Patent is:

1. A corrosion inhibitor composition for addition to aqueous solutionsnormally corrosive to metal surfaces consisting essentially of to 50% ofa primary rosin amine and a complement of a material of the formula)CHzCHzOhEI RN having a molecular weight between about 500 and about2000, where R is a radical selected from the group consisting ofabietyl, hydroabietyl, and dehydroabietyl and where m and n are integerssuch that the molecular weight is within the above-designated range.

3. A corrosion inhibitor composition for addition to aqueous solutionsnormally corrosive to metal surfaces consisting essentially of 5 to 50%of a hydrogenated rosin amine and a complement of a material of theformula )CH; CH2O)mH RN\ having a molecular weight between about 500 andabout 2000, where R is a radical selected from' the group consisting ofabietyl, hydro- 5. A corrosion inhibitor composition for addi- .tion toaqueous solutions normally corrosive to metal surfaces consistingessentially of 5 to 25 of a primary dehydrogenated rosin amine and acomplement of a polyethylene glycol ether of an N-diethanol rosin amineof molecular weight between about 500 and about 2000.

6. A corrosion inhibitor composition for addition to aqueous solutionsnormally corrosive to metal surfaces consisting essentially of 5 to 25%of a primary dehydrogenated rosin amine and 'a complement of apolyethylene glycol ether of an N-diethanol dehydrogenated rosin amine,the molecular weight of said etherbein g between about 500 and 2000.

7. A corrosion inhibitor composition for addition to aqueous solutionsnormally corrosive to metal surfaces consisting essentially of 5 to 25%of a primary hydrogenated rosin amine and a complement of a polyethyleneglycol ether of an N-diethanol rosin amine of molecular weight betweenabout 500 and about 2000.

8. A corrosion inhibitor composition for addition to aqueous solutionsnormally corrosive to metal surfaces consisting essentially of 5 to 25%of a primary hydrogenated rosin amine and a complement of a polyethyleneglycol ether of an N-diethanol hydrogenated rosin amine, the molecularweight of said ether being between about 500 and 2000.

9. A corrosion inhibited aqueous composition comprising an aqueoussolution normally corrosive toward metal surfaces selected from thegroup consisting of aqueous brine solutions and aqueous mineral acidsolutions, said solution containing dissolved therein, in small amountssufiicient to inhibit corrosion of metal surfaces by said solution, thecomposition of claim 1.

10. A corrosion inhibited aqueous composition comprising an aqueousbrine solution normally corrosive toward metal surfaces containingdissolved therein, in smallamounts sumcient to inhibit corrosion ofmetal surfaces by said solution, the composition of claim 1.

11. A corrosion inhibited aqueous composition comprising an aqueousmineral acid solution normally corrosive toward metal surfacescontaining dissolved therein, in small amounts sufficient to inhibitcorrosion of metal surfaces by said solution, the composition of claim1.

12. A corrosion inhibited aqueous composition comprising an aqueousmineral acid solution normally corrosive toward metal surfacescontaining dissolved therein, in small amounts sumcient to inhibitcorrosion of metal surfaces by said solution, the composition of claim2.

13. A corrosion inhibited aqueous composition comprising an aqueousmineral acid solution normally corrosive toward metal surfacescontaining dissolved therein, in small amounts sufficient to inhibitcorrosion of metal surfaces by said solution, the composition of claim3.

14. A corrosion inhibited aqueous composition comprising an aqueousmineral acid solution normally corrosive toward metal surfacescontainin: dissolved therein, in small amounts sufilcient .to inhibitcorrosion of metal surfaces by said solution, the composition of claim4.

15. A corrosion inhibited aqueous composition comprising an aqueousmineral acid solution 5 corrosion of metal surfaces by said solution,the composition of claim 8.

none H. HAGGARD.

REFERENCES CITED The following references are of record in the flle ofthis patent:

uurran sums PATENTS m Number Name Date 2,194,429 Krzikaller Mar. 19,1940 2,367,001 Campbell Jan. 9, 1945 2,510,063 Bried June 8, 1950Certificate of Correction Patent No. 2,564,758

HOMER H. HAGGARD August 21, 1951 It is hereby certified that errorappears in the printed specification of the above numbered patentrequiring correction as follows:

Column 2, line 3, for Table I, read the table; line 7, for weight readweighed; column 7, line 11, before an insert compmsmg; column 8, line 11under UNITED STATES PATENTS for Krzikaller read Krzz'kaZla;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOifice.

Signed and sealed this 6th day of November, A. D. 1951.

moms F. MURPHY,

Am'ctdnt flommim'oncr of Patent:-

1. A CORROSION INHIBITOR COMPOSITION FOR ADDITION TO AQUEOUS SOLUTIONSNORMALLY CORROSIVE TO METAL SURFACES CONSISTING ESSENTIALLY TO 5 TO 50%OF A PRIMARY ROSIN AMINE AND A COMPLEMENT OF A MATERIAL OF THE FORMULA